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 A053289 First differences of consecutive perfect powers (A001597). 16
 3, 4, 1, 7, 9, 2, 5, 4, 13, 15, 17, 19, 21, 4, 3, 16, 25, 27, 20, 9, 18, 13, 33, 35, 19, 18, 39, 41, 43, 28, 17, 47, 49, 51, 53, 55, 57, 59, 61, 39, 24, 65, 67, 69, 71, 35, 38, 75, 77, 79, 81, 47, 36, 85, 87, 89, 23, 68, 71, 10, 12, 95, 97, 99, 101, 103, 40, 65, 107, 109, 100 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Michel Waldschmidt writes: Conjecture 1.3 (Pillai). Let k be a positive integer. The equation x^p - y^q = k where the unknowns x, y, p and q take integer values, all >= 2, has only finitely many solutions (x,y,p,q). This means that in the increasing sequence of perfect powers [A001597] the difference between two consecutive terms [the present sequence] tends to infinity. It is not even known whether for, say, k=2, Pillai's equation has only finitely many solutions. A related open question is whether the number 6 occurs as a difference between two perfect powers. See Sierpiński [1970], problem 238a, p. 116. - Jonathan Vos Post, Feb 18 2008 REFERENCES W. Sierpiński, 250 problems in elementary number theory, Modern Analytic and Computational Methods in Science and Mathematics, No. 26, American Elsevier, Warsaw, 1970, pp. 21, 115-116. S. S. Pillai, On the equation 2^x - 3^y = 2^X - 3^Y, Bull, Calcutta Math. Soc. 37 (1945) 15-20. LINKS Daniel Forgues and T. D. Noe, Table of n, a(n) for n = 1..10000 Holly Krieger and Brady Haran, Catalan's Conjecture, Numberphile video (2018) M. Waldschmidt, Open Diophantine problems, arXiv:math/0312440 [math.NT], 2003-2004. FORMULA a(n) = A001597(n+1) - A001597(n). - Jonathan Vos Post, Feb 18 2008 EXAMPLE Consecutive perfect powers are A001597(14) = 121, A001597(13) = 100, so a(13) = 121 - 100 = 21. MATHEMATICA Differences@ Select[Range@ 3200, # == 1 || GCD @@ FactorInteger[#][[All, 2]] > 1 &] (* Michael De Vlieger, Jun 30 2016, after Ant King at A001597 *) CROSSREFS Cf. A053707, first differences of consecutive perfect prime powers. Cf. A001597, A025475, A053707, A069623, A219551. Sequence in context: A016607 A262216 A076446 * A076412 A053707 A075052 Adjacent sequences:  A053286 A053287 A053288 * A053290 A053291 A053292 KEYWORD nonn AUTHOR Labos Elemer, Mar 03 2000 STATUS approved

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Last modified April 16 07:59 EDT 2021. Contains 343030 sequences. (Running on oeis4.)